HUGE delay in sage.crypto.sbox.SBox method nonlinearity() introduced in v.8.2

savecancel

Average time in nonlinearity() in v.8.1. was *200 ms Average time in nonlinearity() in v.8.2 is 5.1 s*

Here is the code I have used in order to track the issue:

sage: for j in range(10):
....:     S = [x for x in range(256)];shuffle(S)
....:     S = sage.crypto.sbox.SBox(S)
....:     %time S.nonlinearity()

Results from Sage 8.1

CPU times: user 237 ms, sys: 1.87 ms, total: 239 ms
Wall time: 236 ms
94
CPU times: user 208 ms, sys: 12.5 ms, total: 220 ms
Wall time: 220 ms
94
CPU times: user 287 ms, sys: 1.41 ms, total: 288 ms
Wall time: 288 ms
92
....

Results from Sage 8.2

CPU times: user 5.12 s, sys: 30.6 ms, total: 5.15 s
Wall time: 5.16 s
92
CPU times: user 5.04 s, sys: 14.3 ms, total: 5.05 s
Wall time: 5.05 s
96
CPU times: user 5.08 s, sys: 13 ms, total: 5.09 s
Wall time: 5.09 s
94
CPU times: user 5.03 s, sys: 8.56 ms, total: 5.04 s
Wall time: 5.04 s
92
.....